Vented fuel tank cap

ABSTRACT

A vented fuel tank cap for closing the filler neck portion of a fuel tank for a small gasoline powered implement. The fuel tank cap assembly includes a cap member having threads for removably attaching the cap assembly to the fuel tank filler neck. The cap member also includes a post depending from an interior of the cap member. The cap assembly further including a gasket having an annular rim surrounding a dome portion and an opening. The opening of the gasket is disposed on the post and retained by a rib protruding externally from the post. The gasket dome portion is deformed by the rib so that the annular rim is held in contact with the interior surface of the cap member. A vent path is provided through the post to vent fuel vapors from below a lower surface of the gasket, through a filter element captured between the gasket dome and the interior surface of the cap member, through a groove defined between the gasket annular rim and the interior surface of the cap member, and out through a space defined between the threads retaining the cap member to the filler neck.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention.

[0002] The present invention relates to fuel tank caps for closing the filler neck of a fuel tank of a small internal combustion engine, particularly to a vented fuel tank cap.

[0003] 2. Description of the Related Art.

[0004] Small implements having gasoline powered engines, such as lawnmowers, garden tillers, snow blowers, sport vehicles, electrical generators and the like, have fuel tanks attached. For closing the fuel tank, a fuel tank cap is applied to the open end of a filler neck connected to and extending from the fuel tank. The fuel tank cap is commonly constructed to prevent escape of liquid fuel from the fuel tank while, at the same time, permitting venting of gases between the tank and the atmosphere.

[0005] One known fuel tank cap includes a generally dome-shaped flexible gasket extending below the interior of the fuel tank cap. The lower dome portion of the fuel tank cap includes holes therethrough for venting of vapors. Additionally, sufficient clearance is provided between internal threads on the fuel tank cap and external threads on the filler neck to define a path for venting of vapors. A narrow central post depends from the interior of the fuel tank cap and through the gasket. Below the gasket and vent holes, the central post also supports a baffle for deflecting liquid fuel away from the gasket vent holes. However, an extra manufacturing step is required to heat deform the end of the central post so that it will retain the baffle and gasket, adding expense and complexity to manufacturing.

[0006] Another known fuel tank cap includes a dome-shaped flexible gasket having a central vent hole and an integral downward depending tubular-shaped baffle around the vent hole which deflects liquid fuel away from the vent hole. The gasket has an annular rim that is retained by a matching annular notch in the fuel tank cap. However, separation of the gasket and baffle from the fuel tank cap is often a problem when the fuel tank cap is removed from the filler neck. Additionally, a separated or misaligned gasket may not properly seal between the fuel tank cap and the filler neck, resulting in liquid gas venting from the fuel tank.

[0007] Therefore, what is needed is a fuel tank cap assembly that better retains the flexible gasket component thereof while minimizing the number of components and assembly steps.

BRIEF SUMMARY OF THE INVENTION

[0008] The present invention provides an improved vented fuel tank cap assembly. The vented fuel tank cap assembly includes a cap member having a disk-shaped cover portion and a cylindrical skirt portion extending therefrom. The cylindrical skirt portion includes internal threads for engagement to matching external threads located on the fuel tank neck portion. The internal and external threads cooperate to define a vent path therebetween. The cap member includes a tubular central post depending downward from the interior of the cover portion. Advantageously, the tubular central post is integral with the cap member. A filter element having a central hole for receiving the central post is located adjacent the interior of the cover portion. The filter element is held in position by a gasket having an annular rim surrounding a dome portion, the dome portion having a central hole disposed on the central post and compressing the filter against the interior cover portion. The annular rib around an outside diameter of the central post retains the gasket to the cap member slightly deforming the dome portion and sealing the annular rim against the interior surface of the cap member. Radial grooves are provided on the upper surface of the annular rim, i.e., the surface in contact with the interior surface of the cover portion.

[0009] The components of the vented fuel tank cap assembly are easily assembled. First, the filter element is slid onto the central post of the cap member, so that one side of the filter element is against the interior of the cover portion and the central post extends through the hole in the filter element. Second, the gasket is slid onto the central post, the dome portion extending away from the cap member. The dome portion is pressed toward the cap member cover portion, compressing and capturing the filter element, until the dome portion hole passes over the annular rib or other protuberance protruding from the central post. In this position, the annular rib retains the gasket and the filter element to the cover member and the annular rim is held in contact with the interior surface of the cover portion.

[0010] The assembled fuel tank cap provides a vent path for exchanging gases between the fuel tank and the surrounding atmosphere. The vent path is provided from the downward-depending end of the tubular central post, through the central post wall, through the porous filter element, through the grooves provided in the upper surface of the annular rim, and outwardly through the nonsealing threads of the cylindrical skirt member and neck filler portion to the surrounding atmosphere.

[0011] Advantageously, the vented fuel tank cap assembly firmly retains the gasket and filter element to the cap member. Also, the annular rim is held in position by the central post rib so that a seal is formed between the gasket and the filler neck end portion when the fuel tank cap is attached to the fuel tank. Additionally, the filter element and gasket are easily assembled with the cap member using a single step of positioning the filter element and gasket over the central post and rib. Thus, no additional manufacturing steps are required to complete the assembly or retain the components in position.

[0012] In one form thereof, the vented fuel tank cap assembly includes a cap member having a circular cap portion and a downwardly depending skirt portion, the skirt portion including an engagement portion for removably attaching the cap assembly to a filler neck portion of a fuel tank, the cap portion including a cylindrical post depending from an interior of the cap portion, the post having at least one rib extending exteriorly around at least a portion thereof. The cap assembly further includes a gasket having an annular rim surrounding a dome portion and an opening in the dome portion, wherein the opening fits around the post and the rib retains the gasket to the cap member.

[0013] In another form thereof, the vented cap assembly includes a cap member having a circular cap portion and a downwardly depending skirt portion—the skirt portion including an engagement portion for removably attaching the cap assembly to a filler neck portion of a fuel tank, the cap portion including a post depending from an interior of the cap portion; and a circular gasket having an opening defined therethrough, an upper surface engageable with the interior surface of the cap portion, and a lower surface opposite the upper surface, the opening disposed around the central post; the post defining a vent path for communication of gases adjacent the lower surface with gases adjacent the upper surface.

[0014] In yet another form thereof, the vented fuel tank cap assembly for a filler neck end portion of a fuel tank includes a cap member having a circular cap portion and a downwardly depending skirt portion, the skirt portion including nonsealing threads for removably attaching the cap assembly to the filler neck end portion, the cap portion including a tubular post depending from an interior surface of the cap portion, an interior surface of the tubular post defining a first deflection surface and a first vent path therethrough; and a gasket having an annular rim surrounding a dome portion and an opening defined in the dome portion, the opening engaged around the tubular post, the gasket and an exterior surface of the tubular post defining a second deflection surface; the annular rim contacting the interior of the cap portion and forming at least one second vent path therebetween.

[0015] In another form thereof, in combination, a fuel tank having a fuel tank neck portion, and a fuel tank cap having: a cap member including a circular cap portion and a downwardly depending skirt portion, the skirt portion including an engagement portion for removably attaching the cap to the filler neck portion, the cap portion including a tubular post depending from an interior of the cap portion, the tubular post having a rib extending exteriorly around at least a portion thereof; and a gasket having an annular rim surrounding a dome portion and an opening in the dome portion, wherein the opening fits around the tubular post and the rib retains the gasket to the cap member.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0016] The above-mentioned and other features and advantages of the invention, and the manner of obtaining them, will become more apparent and the invention itself will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein:

[0017]FIG. 1 is a side perspective view of a lawnmower having a small internal combustion engine, a fuel tank, and a fuel tank cap assembly in accordance with the present invention;

[0018]FIG. 2 is a side perspective view of a portion of the engine of the lawnmower of FIG. 1, showing the fuel tank cap assembly;

[0019]FIG. 3 is a sectional view taken along line 3-3 of FIG. 1;

[0020]FIG. 4 is an exploded perspective view from above of the fuel tank cap assembly of FIG. 1; and

[0021]FIG. 5 is an exploded perspective view from below of the fuel tank cap assembly of FIG. 1.

[0022] Corresponding reference characters indicate corresponding parts throughout the several views. The exemplification set out herein illustrates an exemplary embodiment of the invention, and such exemplification is not to be construed as limiting the scope of the invention in any manner.

DETAILED DESCRIPTION

[0023] Referring to FIGS. 1 and 2, lawnmower 10 having a small internal combustion engine includes fuel tank 14. Fuel tank 14 has an open filler neck end portion 16 (FIG. 2) providing an opening therein for filling fuel tank 14 with fuel. Vented fuel tank cap assembly 12 is attached to filler neck end portion 16 to prevent liquid fuel from escaping fuel tank 14. Lawnmower 10 is an exemplary implement. Vented fuel tank cap assembly 12 may also be attached to a fuel tank filler neck end portion on other types of small implements having gasoline powered engines, for example garden tillers, snow blowers, sport vehicles, and electric generators. Alternatively, vented fuel tank cap assembly 12 may be attached to other tanks or reservoirs requiring venting of vapors.

[0024] Referring now to FIGS. 3-5, vented fuel tank cap assembly 12 generally includes cap member 31, filter element 18, and gasket 20. Gasket 20 is attached to cap member 31 and captures filter element 18 between cap member 31 and gasket 20.

[0025] Referring to FIG. 3, cap member 31 includes disk-shaped cover portion 32 and downwardly depending cylindrical skirt portion 33. The interior of skirt portion 33 defines threads 39 that engage filler neck threads 17 defined on the outside of filler neck end portion 16. The fit and engagement of cap member threads 39 with filler neck threads 17 retains cap member 31 to filler neck 16 while defining a vent passage therebetween for escape of fuel vapors.

[0026] Depending downwardly from interior surface 34 of cover portion 32 is central post 35. Central post 35 is shown as generally tubular, having a cylindrically-shaped exterior surface 36 and a cylindrically-shaped interior surface 37. Central post 35 is integrally formed with cap member 31, which may be molded of plastic or other similar material. Post 35 may be another shape, such as a square or triangular cross-section, for example. Additionally, post 35 may depend from the center of cover portion 32 or from another part of cover portion 32.

[0027] Referring to FIGS. 4 and 5, gasket 20 includes an annular generally flattened sealing rim 21 surrounding a downwardly depending dome-shaped cavity 24. The central bottom portion of dome 24 defines hole 25 therethrough. Gasket 20 has an upper surface 22 and an opposite lower surface 23. The upper surface 22 of annular rim 21 defines four grooves 28 circumferentially spaced around annular rim 21. Notches 29 are defined on the outside edge of annular rim 21 adjacent each groove 28. Gasket 24 is advantageously made of rubber or other material that is impervious to and non-reactive with liquid fuel and which is flexible.

[0028] Filter element 18 is generally rectangular shaped and defines a hole centrally therethrough. Filter element 18 allows transmission of fuel vapor and atmospheric gases but is generally impervious to liquid fuel. Filter element 18 may be constructed of reticulated flexible polyurethane with open pores of approximately 50 per inch, for example, or other similar porous material which will trap liquid fuel, yet allows vapors to pass therethrough. Filter element 18 is positioned between cover portion 32 and gasket 20 in dome-shaped cavity 24.

[0029] Fuel tank cap 10 operates to allow fuel vapor to vent from fuel tank 14 and/or to allow atmospheric gases to enter fuel tank 14. As shown in FIGS. 3 and 5, vent path slot 41 is defined vertically along a portion of the length of central post 35. Specifically, slot 41 extends through the tubular wall of central post 35 from the downwardly depending end, toward cover portion 32, ending at slot end 42. Advantageously, slot end 42 is located above the level of dome 24 and adjacent to filter element 18. Additionally, grooves 28 between upper surface 22 of rim 21 and interior surface 34 of cap portion 31 and notches 29 define a vent path therethrough. Thus, fuel vapor escapes fuel tank 14 by passing from the interior of central post 35, through vent path 41 at slot end 42, through porous filter element 18, and into the space defined between gasket dome 24 and cover portion 32. The vent path for escaping fuel vapors continues through grooves 28 and notches 29 between annular rim 21 and cover portion interior surface 34, and between nonsealing threads 39 and filler neck threads 17.

[0030] Referring to FIG. 3, the vented fuel cap assembly 12 is assembled as follows. Hole 19 of filter element 18 slides onto central post 35 until a surface of the filter is compressed against interior surface 34 of cover portion 32. Gasket 20 then slides onto central post 35 until hole 25 passes over and is engaged by annular rib 43 defined around an external portion of central post 35, thereby retaining gasket 20 to cap member 31. In this engaged position, gasket 20 is firmly retained to cap member 31, and dome 24 is slightly deformed toward cap member 31 and annular rim 21 is sealingly compressed against interior surface 34 of cover portion 32. Rib 43 may be a single annular protuberance defined around part of or the entire diameter of central post 35, or may alternatively be a segmented series of protuberances, a single protuberance, or other arrangement of protuberances.

[0031] In this arrangement, vented cap assembly 12 may be threadably engaged to filter neck end portion 16 and operates to prevent liquid fuel from escaping fuel tank 14 while providing venting of fuel vapors to the atmosphere. As cap member 31 is screwed onto filler neck end portion 16, annular rim 21 of gasket 20 is captured between a top end of filler neck end portion 16 and interior surface 34 of cover portion 32, thus forming a seal between lower surface 23 of rim 21 and filler neck portion 16.

[0032] In this installed position, vented cap assembly 12 forms two deflection surfaces that resist venting of liquid fuel from fuel tank 14. The first is formed by exterior surface 36 of central post 35 and by gasket 24 which is sealably pressed against the upper end of filler neck end portion 16. The second deflection surface is defined by the interior surface 37 of central post 36. The deflection surfaces reduce splashing of liquid fuel toward the vent path, thus ensuring only fuel vapors are vented.

[0033] The escape of liquid fuel from fuel tank 14 is further prevented by the difficulty of liquid fuel reaching vent path 41 along slot end 42 and the resistance of filter element 18 to the flow of liquid fuel. Liquid fuel that reaches filter element 18 will be drained by gravity back through vent path 41 and back into fuel tank 14.

[0034] While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character. It should be understood that only the preferred embodiments have been shown and described and that all changes and modifications that come within the spirit of the invention are desired to be protected. 

What is claimed is:
 1. A vented fuel tank cap assembly, comprising: a cap member including a circular cap portion and a downwardly depending skirt portion, said skirt portion including an engagement portion for removably attaching the cap assembly to a filler neck portion of a fuel tank, said cap portion including a cylindrical post depending from an interior of said cap portion, said post having at least one rib extending exteriorly around at least a portion thereof; and a gasket having an annular rim surrounding a dome portion and an opening in said dome portion, wherein said opening fits around said post and said rib retains said gasket to said cap member.
 2. The vented fuel tank cap assembly of claim 1, further comprising a porous filter element disposed between said dome portion of said gasket and said interior of said cap portion, wherein said filter element transmits fuel vapors and is generally impervious to liquid fuel.
 3. The vented fuel tank cap assembly of claim 2, wherein said rib deforms said dome portion of said gasket compressing said filter element between said dome portion and said interior of said cap portion.
 4. The vented fuel tank cap assembly of claim 1, wherein said engagement portion comprises threads cooperating to retain the fuel cap to said fuel tank while providing a vent path therethrough.
 5. The vented fuel tank cap assembly of claim 1, further comprising a vent path for venting gases between the fuel tank and the atmosphere defined by said post from an end of said post opposite said interior of said cap portion to a point between said dome portion and said interior of said cap portion.
 6. The vented fuel tank cap assembly of claim 5, wherein: said annular rim contacts said interior of said cap portion; and at least one vent path is defined between said annular rim and said interior of said cap portion.
 7. The vented fuel tank cap assembly of claim 5, wherein said post comprises a tube and said vent path comprises a slot defined through a wall of said tube.
 8. A vented fuel tank cap assembly, comprising: a cap member including a circular cap portion and a downwardly depending skirt portion, said skirt portion including a nonsealing thread for removably attaching the cap assembly to the filler neck portion, said cap portion including a tubular post depending from an interior of said cap portion, an interior surface of said tubular post defining a first deflection surface and a first vent path; and a gasket having an annular rim surrounding a dome portion and an opening defined in said dome portion, said opening engaged around said tubular post, said gasket and an exterior surface of said tubular post defining a second deflection surface, said annular rim contacting said interior of said cap portion and forming at least one second vent path therebetween.
 9. The vented fuel tank cap assembly of claim 8, wherein said first vent path comprises a slot defined through a wall of said tubular post.
 10. The vented fuel tank cap assembly of claim 8, wherein said at least one second vent path is formed by at least one radial groove defined between an upper surface of said annular rim and said interior of said cap portion.
 11. The vented fuel tank cap assembly of claim 8, wherein said post defines a rib protruding externally around a portion thereof, said rib retaining said gasket to said cap member.
 12. The vented fuel tank cap assembly of claim 8, further comprising a porous filter element disposed between said dome portion of said gasket and said interior of said cap portion, wherein said filter element transmits fuel vapors and is generally impervious to liquid fuel.
 13. The vented fuel tank cap assembly of claim 12, wherein said rib deforms said dome portion of said gasket, compressing said filter element between said dome portion and said interior of said cap portion.
 14. A vented fuel tank cap assembly, comprising: a cap member including a circular cap portion and a downwardly depending skirt portion, said skirt portion including an engagement portion for removably attaching the cap assembly to a filler neck portion of a fuel tank, said cap portion including a post depending from an interior of said cap portion; and a circular gasket having an opening defined therethrough, an upper surface engageable with said interior of said cap portion, and a lower surface opposite said upper surface, said opening disposed around said post; said post defining a first vent path for communication of gases adjacent said lower surface with gases adjacent said upper surface.
 15. The vented fuel tank cap assembly of claim 14, wherein said post comprises a tube and said vent path comprises a slot defined through a wall of said tube.
 16. The vented fuel tank cap assembly of claim 14, wherein said at least one second vent path is formed by at least one radial groove defined between an upper surface of said annular rim and said interior of said cap portion.
 17. The vented fuel tank cap assembly of claim 14, wherein said post defines a rib around an external portion thereof, said rib retaining said gasket to said cap member.
 18. The vented fuel tank cap assembly of claim 17, further comprising a porous filter element disposed between said gasket and said interior of said cap portion, wherein said filter element transmits fuel vapors and is generally impervious to liquid fuel.
 19. The vented fuel tank cap assembly of claim 18, wherein: said gasket further comprises a dome portion; and said rib captures said filter element between said dome portion and said interior of said cap portion.
 20. The vented fuel tank cap assembly of claim 14, wherein said engagement portion comprises threads cooperating to retain the fuel cap to said fuel tank while providing a vent path therethrough.
 21. In combination: a fuel tank having a fuel tank neck portion; and a fuel tank cap having: a cap member including a circular cap portion and a downwardly depending skirt portion, said skirt portion including an engagement portion for removably attaching said cap to said filler neck portion, said cap portion including a tubular post depending from an interior of said cap portion, said tubular post having at least one rib extending exteriorly around at least a portion thereof; and a gasket having an annular rim surrounding a dome portion and an opening in said dome portion, wherein said opening fits around said tubular post and said rib retains said gasket to said cap member. 